Graphene composite acoustic diaphragm

ABSTRACT

The disclosure relates to an audio device that includes a diaphragm having a graphene material, such as a graphene flake, that is incorporated into a base material. The audio device may form part of a speaker device, a microphone device, or a headphone device. The concentration of the graphene and/or a size of the graphene flakes may be varied throughout the diaphragm to define a stiff center portion and a flexible portion that surrounds the center portion.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/788,205, for “GRAPHENE COMPOSITE ACOUSTIC DIAPHRAGM” filed on Jun.30, 2015, which is hereby incorporated by reference in their entiretyfor all purposes.

FIELD

Embodiments described herein generally relate to the field of acousticsystems and, more specifically, to an acoustic device that includes adiaphragm having one or more portions formed using graphene.

BACKGROUND

Audio functionality is an important aspect of various electronicdevices. For example, laptop computers, tablets, mobile telephones, andthe like may all include some type of acoustic speaker and/or microphoneto transmit and/or receive audio signals. As devices become smaller andlighter, it becomes more difficult to provide high-quality audio devicesusing conventional materials. In particular, it may be challenging toproduce an audio device that is compact and lightweight while alsoproviding a desired audio performance.

SUMMARY

Embodiments described herein may relate to, include, or take the form ofacoustic devices having a diaphragm that incorporates a graphenematerial, such as graphene flakes. In some embodiments, a polymercomposite may include graphene flakes and form at least a portion of adiaphragm. The polymer composite may be used to make the diaphragmthinner, stiffer, and/or lighter.

Some example embodiments are directed to an audio device including asupport structure and an acoustic element that is disposed within arecess of the support structure. The audio device also includes adiaphragm that is coupled to the support structure. The diaphragm mayinclude a center portion formed from a base material and a grapheneflake material that is incorporated into the base material. Thediaphragm also includes a flexible portion that surrounds the centerportion. The flexible portion may be coupled to the support structureand may be configured to flex in response to a movement of the centerportion with respect to the support structure or acoustic element. Insome embodiments, the base material comprises a polymer and the grapheneflake material is molded into the polymer material.

In some embodiments, the center portion has a first stiffness that isgreater than a second stiffness of the flexible portion. The centerportion may include a first concentration of graphene flakes and theflexible portion may include a second concentration of graphene flakes.The first concentration may be greater than the second concentration. Insome embodiments, the center portion includes a first size of grapheneflake and the flexible portion includes a second size of graphene flake.The first size may be greater than the second size resulting in astiffer center portion.

In some embodiments, the center portion includes a membrane structureand a composite cap structure that is bonded to a surface of themembrane structure. A portion of the membrane structure may form theflexible portion of the diaphragm. The diaphragm may form a conical domeshape or other similar contoured shape.

In some embodiments, the audio element includes a magnet that isdisposed within the recess of the support structure. A voice coil may beattached to the center portion of the diaphragm and may beelectromagnetically coupled to the magnet. The flexible portion may beconfigured to flex in response to relative motion between the magnet andthe voice coil. The audio device may form a speaker, a headphone, amicrophone, or other similar device.

Some example embodiments are directed to a portable electronic devicethat includes a housing that defines an opening. A display may bepositioned in the opening of the housing. A processor may be coupled tothe display and an audio device. The audio device may include a supportstructure and a diaphragm that is flexibly connected to the supportstructure. The diaphragm may be formed from graphene that isincorporated into a base material. The concentration of the graphene mayvary within the diaphragm to define a center portion and a flexibleportion such that the center portion is stiffer than the flexibleportion. The diaphragm may be configured to transmit and/or receivesound waves.

In some embodiments, the center portion includes an inner center portionand an outer center portion that surrounds the inner center portion. Theouter center portion may have a graphene concentration that is lowerthan a graphene concentration of the inner center portion. The flexibleportion may include a graphene concentration that is lower than thegraphene concentration of the outer center portion.

The diaphragm may form a conically shaped dome structure. The conicallyshaped dome structure may define an edge portion surrounding theflexible portion in a location where the edge portion is attached to thesupport structure. In some embodiments, a graphene concentration of theedge portion is greater than the graphene concentration of the flexibleportion.

Some example embodiments are directed to a method for manufacturing adiaphragm for an audio device. The method may include preparing a basematerial and adding graphene flakes to the base material to create acomposite mixture. The method may also include forming a diaphragm bymolding the composite mixture. In some cases, the diaphragm is installedin an acoustic device. In some embodiments, adding the graphene flakesincludes varying the concentration of the graphene flakes to form two ormore distinct portions of the diaphragm. In some cases, the basematerial comprises a polymer and the molding process includes aninjection molding process.

The diaphragm may include a dome structure. A first concentration ofgraphene flakes may be increased in a center portion of the domestructure as compared to a second concentration of graphene flakes in aflexible portion surrounding the center portion.

In some embodiments, the composite mixture is a first composite mixturehaving a first concentration and/or first size of graphene flakes.Graphene flakes may be added to the base material to create a secondcomposite mixture having a second concentration and/or size of grapheneflakes. The first concentration may be greater than the secondconcentration and/or the first size graphene flake may be greater thanthe second size of graphene flake. A center portion of the diaphragm maybe molded using the first composite mixture. A flexible portion of thediaphragm surrounding the center portion may be molded using the secondcomposite mixture.

Forming the diaphragm may further comprise forming an inner centerportion having a first concentration of graphene flakes and forming anouter center portion having a second concentration of graphene flakesthat is lower than the first concentration. A flexible portion may alsobe formed having a third concentration of graphene flakes that is lowerthan the second concentration.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure will be readily understood by the following detaileddescription in conjunction with the accompanying drawings, wherein likereference numerals designate like structural elements, and in which:

FIG. 1 depicts an example electronic device including an audio device;

FIG. 2 is a cross-sectional view of a speaker device taken along sectionA-A;

FIG. 3 is a cross-sectional view of a microphone device taken alongsection B-B;

FIG. 4 is a cross-sectional view of an embodiments of a diaphragm takenalong section A-A;

FIG. 5 is a cross-sectional view of another embodiment of a diaphragmtaken along section A-A;

FIG. 6 is a process flow diagram of a process for making a diaphragmincluding graphene; and

FIG. 7 is an illustrative block diagram of an electronic device.

DETAILED DESCRIPTION

Reference will now be made in detail to representative embodimentsillustrated in the accompanying drawings. It should be understood thatthe following descriptions are not intended to limit the embodiments toone preferred embodiment. To the contrary, it is intended to coveralternatives, modifications, and equivalents as can be included withinthe spirit and scope of the described embodiments as defined by theappended claims.

The following disclosure relates to a diaphragm formed from a compositegraphene material. In general, the physical characteristics of adiaphragm may affect the performance of an audio device, such as aspeaker or microphone. In particular, the acoustic performance of aspeaker may depend, at least in part, on the geometry and/or structuralproperties of the diaphragm. In general, a speaker may include an audioelement, such as a transducer (e.g., voice coil), that converts anelectrical signal into movement of a diaphragm. Movement of thediaphragm may produce a pressure differential that forms sound waves orother acoustic response. The performance of the speaker may bequantified by the degree of correlation between the electrical signalprovided to the speaker and the mechanical response of the transducerand diaphragm.

The correlation between an electrical input and the mechanical output ofa speaker may not be perfect due to practical limitations of thehardware. Variability in the correlation between the electrical signaland the mechanical or acoustic response may sometimes be referred to asdistortion. In general, a diaphragm having a high stiffness and lightweight may allow a speaker transducer to react more quickly, which mayminimize or reduce distortion of the electrical signal. Therefore, itmay be advantageous to use a material that has a high strength to weightratio.

Achieving low distortion in small audio devices is particularlychallenging. Using some traditional materials, the mass of the diaphragmmay be too high for a small or compact transducer, which may result inunacceptable levels of distortion. In some cases, the distortion may bereduced by using a mechanical damper. However, mechanical dampers mayincrease the complexity and cost as well as reduce the power efficiencyof the audio device.

The embodiments described herein are directed to acoustic devices havinga diaphragm incorporating a graphene or graphene flake material, whichmay increase the stiffness of the diaphragm without significantlyincreasing the weight. The graphene may be included in a graphene-flakecomposite polymer material that is molded or otherwise formed into thediaphragm component. The composite polymer may be used to make thediaphragm thinner, stiffer, and/or lighter, as compared to sometraditional diaphragm materials. In some embodiments, a graphenecomposite polymer may be used to create smaller acoustic devices withoutsignificantly compromising audio quality.

In some implementations, using a graphene flake material may improve themechanical response of the audio device. In particular, a diaphragmformed from a graphene or graphene flake material may be configured tohave a mass and spring constant that is tuned to provide a particularmechanical or acoustic response. In some cases, the use of graphene orgraphene flake material may reduce or eliminate the need for additionalexternal damping. Graphene may be used to produce a light diaphragm witha low spring constant (e.g., stiffer), which may eliminate the need fora separate damping mechanism, which may reduce complexity of the audiodevice. A reduction in dampening may also improve the efficiency andreduce the power consumption of the audio device.

In some embodiments described herein, the concentration of the graphenemay be varied throughout the diaphragm to provide a structure havingparticular mechanical properties. In particular, a higher concentrationof graphene may be used in a center portion of the diaphragm to increasestiffness and possibly reduce the weight of the moving mass. A lowerconcentration of graphene may be used in a flexible portion or otherportion to increase the flexibility of select regions of the diaphragm.

In some embodiments described herein, the graphene includes a grapheneflake that may be configured to provide particular mechanicalproperties. In some cases, the size of the graphene flake may be variedthroughout the diaphragm to provide a structure having the desiredstiffness or flexibility. In some implementations, the center portionmay include a first size of graphene flake that is larger than a secondsize of graphene flake in the flexible portion. An increased size of thegraphene flake may result in a stiffer center portion as compared to theflexible portion. The graphene flakes may also be oriented or alignedalong one or more directions to provide particular mechanicalproperties. In particular, the a flake area of the graphene flakes maybe substantially aligned with an outer or inner surface of thediaphragm.

While the examples described herein are directed to a graphene materialin the form of a graphene flake, the examples may also apply to otherforms of graphene. In particular, instead of graphene flake, theembodiments described herein may use a graphene flake stack, graphenefiber, graphene sheet, graphene spheres, graphene clusters, graphenechips, graphene particles, and so on. A combination of graphenematerials may also be used to form the composite graphene diaphragm.

Some embodiments are directed to a method for manufacturing a diaphragmfor an audio device, such as a speaker or microphone device. The methodmay include forming two or more distinct portions of the diaphragm usingdifferent concentrations of and/or different size graphene flakes. Insome embodiments, variable amounts of graphene are incorporated into abase diaphragm material to provide a diaphragm having different levelsof stiffness in different regions. In some cases, the stiffness of thediaphragm can be increased without significantly changing the mass ofthe diaphragm, which may reduce or eliminate the need for inclusion ofadditional mechanical damping mechanisms or elements in the audiodevice.

These and other embodiments are discussed below with reference to FIGS.1-7. However, those skilled in the art will readily appreciate that thedetailed description given herein with respect to these Figures is forexplanatory purposes only and should not be construed as limiting.

In general, a diaphragm that includes graphene, such as a grapheneflake, may be incorporated into a variety of acoustic devices including,for example, a speaker or a microphone of an electronic device. FIG. 1depicts an example electronic device 101 that includes both a speakerdevice 106 and microphone device 107 (example audio devices). Asdescribed in more detail below, the speaker device 106 and/or themicrophone device 107 may include a diaphragm that includes orincorporates a graphene or graphene flake material to increase thestiffness of the diaphragm and potentially improve the performance ofthe corresponding audio device(s).

In the example depicted in FIG. 1, the electronic device 101 isimplemented as a smartphone. Other example electronic devices mayinclude, without limitation, a desktop computing device, a notebookcomputing device, a tablet computing device, a wearable electronicdevice, a health monitoring device, a gaming device, a remote controldevice, and other types of electronic and portable electronic devices.While the following description is provided with respect to audiocomponents integrated with an electronic device, the principles of anaudio component having a graphene diaphragm may also be applied toaccessory devices, such as a headphones, headsets, stand-alone speakers,and so on.

As shown in FIG. 1, the electronic device includes a housing 102 thatencloses and protects the internal components of the device 101. Exampleinternal components are described in more detail below with respect toFIG. 7. The housing 102 may define one or more openings for user inputdevices, such as the button 104 depicted in FIG. 1.

The housing 102 may also define an opening in a top surface and adisplay 103 may be disposed or positioned within the opening. Thedisplay 103 may be attached directly to the housing 102 or securedwithin the device 101 using another component. The display 103 mayinclude a liquid crystal display (LCD), organic light emitting diode(OLED) display, electroluminescent (EL) display, or other type ofdisplay element. The display 103 may be configured to provide a visualoutput to the user including, for example, a graphical user interface.The display 103 may also be configured to provide visible media contentincluding video, images, or other graphical content. In some cases, thedisplay 103 may also incorporate a touch sensor for receiving userinput.

As shown in FIG. 1, the device 101 includes a speaker device 106 forproviding audio output to the user. The audio output may correspond tothe visual output provided by the display 103 and/or provide audiofeedback for user input devices, such as the button 104. In someembodiments, the speaker device 106 is configured to provide the audiofor a telephone call or other audible communication. A more detaileddescription of the speaker device 106 is provided below with respect toFIG. 2.

As shown in FIG. 1, the device 101 also includes a microphone device107. The microphone device 107 may be configured to receive audiosignals or input from the user or from a source external to the device101. In some cases, the microphone device 107 is configured to receiveaudio input for a telephone call or other audible communication. A moredetailed description of the microphone device 107 is provided below withrespect to FIG. 3.

As previously discussed, audio devices such as speakers and microphonesmay include a diaphragm component or element. In some cases, it may beadvantageous for the diaphragm to include or incorporate a graphenematerial (e.g., a graphene flake). FIGS. 2 and 3 depict example audiodevices that may use a graphene-based diaphragm.

FIG. 2 depicts a cross-sectional view the speaker device 106 taken alongsection A-A of FIG. 1. As described previously, the speaker device 106may be incorporated with an electronic device (e.g., device 101 ofFIG. 1) and used to produce an audio output. The speaker device 106represents an example configuration of an audio device that includes adiaphragm formed using graphene (e.g., graphene flake). While thespeaker device 106 depicted in FIG. 2 represents an illustrativeexample, the configuration is not intended to be limiting.

As shown in FIG. 2, the speaker device 106 includes a support structure202, a magnet 203, a voice coil 204, and a diaphragm 205. The supportstructure 202 defines a recess 218, which may include a partiallyenclosed portion of the support structure 202 in which an audio element216 is positioned. An example audio element 216, such as anelectromagnetic transducer, may be formed between a magnet 203 and avoice coil 204, which may move with respect to each other in response toan electrical signal provided to the voice coil 204. Changes in theelectromagnetic fields produced by the voice coil 204 (due to theelectrical signal) may result in a motive force between the voice coil204 and the magnet 203. The motive force may produce the relativemovement between the voice coil 204 and the magnet 203. In some cases,the magnet 203 may be described as being electromagnetically coupled tothe voice coil 204.

As shown in FIG. 2, a support structure 202, which may be fixed, iscoupled to the magnet 203. Thus, a motive force between the voice coil204 and the magnet 203 results in a movement of the voice coil 204. Inthe present embodiment, the diaphragm 205 is attached to the voice coil204 such that movement of the voice coil 204 results in a movement of acenter portion 209 of the diaphragm 205 with respect to the supportstructure 202. Movement of diaphragm 205 may cause the diaphragm 205 todisplace air and generate sound waves 208 as a result of a vibratory oroscillatory movement of the voice coil 204. In some embodiments, thesound waves 208 may create the acoustic output or response of thespeaker device 106. As shown in FIG. 2, the diaphragm may include aconical dome shape that may facilitate the formation of the sound waves208.

In the embodiment of FIG. 2, the diaphragm 205 is coupled to the supportstructure 202. In particular, the diaphragm 205 is attached to thesupport structure 202 at edge portion 206. In some embodiments, the edgeportion 206 is located within or adjacent to a flexible portion 207 ofthe diaphragm, which surrounds the center portion 209 of the diaphragm205. In this configuration, the edge portion 206 of the diaphragm 205 isfixed with respect to the support structure 202. Because the centerportion 209 moves in conjunction with the voice coil 204, the centerportion 209 will move with respect to the edge portion 206, which iscoupled to the fixed support structure 202. Thus, the flexible portion207 may be configured to provide compliance between the moving centerportion 209 and the stationary edge portion 206, and may flex inresponse to a movement of the voice coil 204 with respect to the magnet203.

It may be advantageous that the diaphragm have both flexible and stiffregions. In particular, the flexible portion 207 may form a flexible orcompliant portion of the diaphragm 205 to accommodate the movementcaused by oscillation of the voice coil 204. Additionally, to provide asuitable acoustic response, it may be advantageous that the centerportion 209 of the diaphragm 205 be relatively stiff or rigid, which mayresult in sound waves 208 having a consistent and/or suitable audioquality.

Providing a diaphragm 205 that is both stiff or substantially rigid inthe center portion 209 while also flexible or compliant in the flexibleportion 207 may present a significant design challenge, particularly ifthe mass of the diaphragm 205 is very low. One potential solution is toincorporate graphene, such as a graphene flake material 210, into thediaphragm 205 in order increase the stiffness of the center portion 209.In some embodiments, center portion 209 is constructed of a basematerial 214 and a graphene flake material 210 that is incorporated intothe base material 214. In some implementations, the base material 214may include a polymer or other synthetic material.

The diaphragm 205 may include varying amounts of graphene in differentregions or portions to provide both a rigid center portion 209 and aflexible portion 207. In some implementations, the concentration ofgraphene flake material in the center portion 209 is greater than theconcentration of graphene flake material in the flexible portion 207.The greater concentration of graphene flake material may result in thecenter portion 209 having a stiffness that is greater than the flexibleportion 207. In some embodiments, the flexible portion 207 has nographene flakes or a substantially zero graphene flake concentration.Example diaphragms having varying concentrations of graphene flakes aredescribed below with respect to FIGS. 4 and 5.

The diaphragm 205 may also have variations in graphene flake size. Forexample, the center portion 209 may include a first size of grapheneflake and the flexible portion 207 may include a second size of grapheneflake that is smaller than the first size. The decreased size of thegraphene flake may result in a more flexible or pliable flexible portion207 as compared to the center portion 209. Conversely, the increasedsize of the graphene flake may result in a stiffer center portion 209 ascompared to the flexible portion 207.

While varying concentration and/or size of graphene flakes may be usedto vary the stiffness of the diaphragm 205, graphene flakes may also beadded in improve the water resistance of the diaphragm 205. In general,graphene flakes may be substantially impermeable to water and mayfunction as a moisture barrier. Thus, graphene flakes 210 in variousconcentrations may be incorporated into the diaphragm 205 to reduce thewater or moisture permeability of the diaphragm 205 and possibly improvethe water resistance of the speaker 106.

The example diaphragm 205 depicted in FIG. 2 has a conical dome shapedstructure with an outward or convex curvature. It should be understoodthat either a convex or a concave curvature may be used to produce thesound waves 208 and, thus, the specific shape or curvature is notcritical to this embodiment. Additionally, while the example speakerdevice 106 of FIG. 2 depicts the magnet 203 as stationary and the voicecoil 204 as moving, alternative embodiments may be constructed in whichthe voice coil 204 is stationary and the magnet 203 moves.

As shown in FIG. 2, the speaker device 106 may be incorporated into anelectronic device (e.g., device 101 of FIG. 1). In particular, thesupport structure 202 may be coupled to a mounting structure 222 whichattaches the speaker device 106 to the housing 102 of an electricaldevice. The mounting structure 222 may include multiple components orlayers to facilitate mechanical coupling and/or acoustic isolation ofthe speaker device 106 with respect to the housing 102. In someembodiments, the mounting structure 222 includes one or more compliantlayers or gaskets to create an acoustic seal between the speaker device106 and the housing 102. Also, as shown in FIG. 2, the housing 102 maydefine an opening 220 or aperture through which the sound waves 208 maypass. The opening 220 may include a screen or other protective elementto prevent the ingress of contaminants and protect the speaker device106.

In a similar fashion, a diaphragm that includes graphene may be used toform other types of acoustic devices, such as a microphone. In general,a microphone may function as an acoustic-to-electric transducer orsensor that converts sound in air into an electrical signal. In somemicrophone embodiments, sound is first converted to mechanical motionusing a diaphragm. The diaphragm may be coupled to a transducer whichconverts the mechanical motion into an electrical signal.

FIG. 3 depicts a cross-sectional view of an example microphone device107 taken along section B-B of FIG. 1. Similar to the speaker device ofthe previous example, the microphone device 107 includes a diaphragm 305having a graphene flake material 310. In this example, the diaphragm 305is coupled to an audio element 316, such as an electromagnetictransducer, that converts mechanical energy (the motion of the diaphragm305) into an electrical signal. In particular, sound waves 308 may enterthrough the opening 320 of the housing 102 and cause the diaphragm 305to vibrate or oscillate. The diaphragm 305 is coupled to a voice coil304 which is electromagnetically coupled to the magnet 303. Movement ofthe diaphragm 305 (caused by the sound waves 308) produces relativemotion between the voice coil 304 and the magnet 303 resulting in aninduced current in the voice coil 304. The induced current of the voicecoil 304 may form the electrical signal or output of the microphonedevice 107.

While FIG. 3 depicts an audio element 316 including an electromagnetictransducer with a magnet 303 and a voice coil 304, other embodiments mayuse a different type of audio element 316 that is configured to convertmovement into an electrical signal. For example, alternative embodimentsmay use a piezoelectric element that is coupled between the supportstructure 302 and the diaphragm 305 to produce an electrical signal inresponse to vibration or oscillation of the diaphragm 305. The diaphragm305 may form a conical dome shape that may facilitate the reception ofthe sound waves 308.

As shown in FIG. 3, the magnet 303 is positioned in a recess 318 of thesupport structure 302 and may be attached or fixed relative to thesupport structure 302. The support structure 302 is attached to thehousing 102 of the electrical device by a mounting structure 322. Themounting structure 322 may be similar to the mounting structure 222described above with respect to FIG. 2 and may provide both themechanical coupling and acoustic isolation between the microphone device107 and the housing 102.

As shown in FIG. 3, an edge portion 306 of the diaphragm 305 is coupledor attached to the support structure 302. Because the edge portion 306is fixed with respect to the support structure 302 and the centerportion 309 moves in response to the sound waves 308, it may beadvantageous for the flexible portion 307 to be flexible or compliant.Additionally, similar to the speaker example, it may be advantageousthat the center portion 309 be rigid or stiff to improve the sensitivityof the diaphragm 305 in response to an acoustic signal, such as thesound waves 308. Thus, similar to the speaker example, it may beadvantageous to incorporate graphene, such as graphene flake material310 into the diaphragm 305 to increase the stiffness of the centerportion 309 of the diaphragm 305. In some embodiments, center portion309 is constructed of a base material 314 and a graphene flake material310 that is incorporated into the base material 314.

In some embodiments, the diaphragm 305 includes varying amounts ofgraphene in different regions or portions to provide both a rigid centerportion 309 and a flexible portion 307. In some implementations, theconcentration of graphene flake material in the center portion 309 isgreater than the concentration of graphene flake material in theflexible portion 307. The greater concentration of graphene flakematerial may result in the center portion 309 having a stiffness that isgreater than the flexible portion 307. Similarly, a larger grapheneflake may be incorporated into the center portion 309 as compared to theflexible portion 307, which may result in a stiffer center portion 309.The concentration and/or size of the graphene flakes 406 may also beconfigured to reduce the water permeability of the diaphragm 305.Example diaphragms having varying concentrations of graphene flakematerial are described below with respect to FIGS. 4 and 5.

FIG. 4 depicts a cross-sectional view of an example diaphragm 405. Theexample diaphragm 405 may correspond to the diaphragms 205 and 305 ofFIGS. 2 and 3, discussed above. More generally, the diaphragm 405 may beused in a variety of acoustic devices to convert electrical signals intoacoustic energy (e.g., sound waves) or, conversely, convert acousticenergy into an electrical signal. The diaphragm 405 may have a generallydome shaped geometry.

As shown in FIG. 4, the diaphragm 405 may be formed from differentportions having different mechanical properties. Specifically, thediaphragm 405 includes a center portion 402 that is stiffer than theflexible portion 401 that surrounds the center portion. Additionally,the center portion 402 may include an inner center portion 403 that issurrounded by an outer center portion 404 having a different stiffnessthan either the inner center portion 403 and the flexible portion 401.

Varying the stiffness of diaphragm 405 in areas 401, 403, and 404 may bedifficult to accomplish without adversely affecting the mass ofdiaphragm 405, which can affect performance of the audio device. Inaddition, an uneven mass distribution across the diaphragm 405 mayaffect the vibrational response of the diaphragm 405 and adverselyaffect audio performance.

A graphene material, such as a graphene flake material, may beincorporated into the diaphragm to alter the stiffness withoutsignificantly impacting the mass. In general, graphene is pure carbon inthe form of a very thin, flexible, nearly transparent sheet. In somecases, a graphene sheet may be a one atom thick sheet of graphite havingcarbon atoms that are densely packed in a hexagonal pattern. In someembodiments, graphene sheets may be about 0.35 nm or one atom thick. Agraphene sheet may be used to form graphene flakes having a smaller areabut substantially the same thickness.

Graphene may be up to 100 times stronger than steel by weight. Also,because graphene is a very thin material (having a thickness as low asone atom), the mass of a graphene flake can be precisely controlled bycontrolling the surface area or flake size. When a graphene flake isincorporated into a base material, such as a polymer, the stiffness ofthe composite may be precisely controlled without significantlyaffecting the mass. In the present example, the base material 412 may bea polymer material which may include high or low density polyethylene,polypropylene, polyvinyl chloride, polystyrene and thermoplasticpolyurethanes.

In some cases, a graphene flake material 406 may be incorporated into abase material to adjust the stiffness across the diaphragm 405. Embeddedgraphene flake material 406 may result in a diaphragm 405 that isthinner, stiffer and lighter. A light diaphragm with a low springconstant reduces the need for a complex mechanical damping mechanism andthe resultant power loss due to the damping mechanisms. Varying theconcentration of the graphene flake material 406 in various portions ofdiaphragm 405 allows the mass and stiffness of diaphragm 405 to becontrolled to optimize performance. The concentration of the grapheneflake may vary between concentrations as low as 0.001 percent and up toand including 2 percent.

With reference to the diaphragm 405 of FIG. 4, the center portion 402may have a higher concentration of graphene flakes 406, which may resultin a stiffer center portion 402 without increasing the mass of diaphragm405. The concentration of graphene flakes 406 in the center portion 402may be higher relative to a concentration of graphene flakes 406 atflexible portions 401 of the diaphragm 405. The reduced graphene flakeconcentration in the flexible portion 401 may result in a more flexibleor pliable material and facilitate vibration and movement of thediaphragm 405. In some implementations, the flexible portion 401 mayhave no graphene flakes or a substantially zero concentration ofgraphene flakes.

Additionally, the center portion 402 may define two or more regions orportions that have varying levels of stiffness. In some implementations,the middle or inner portion of the center portion 402 is the most stiffand outer portions surrounding the middle of the center portion 402 mayhave decreasing levels of stiffness. In the embodiment depicted in FIG.4, the center portion 402 includes an outer center portion 404 thatsurrounds an inner center portion 403. The outer center portion 404 mayhave a graphene flake material concentration that is lower than thegraphene flake material concentration of the inner center portion 403resulting in a reduced stiffness.

The diaphragm 405 may also have variations in graphene flake size. Forexample, the center portion 402 may include a first size of grapheneflake and the flexible portion 401 may include a second size of grapheneflake that is smaller than the first size. The decreased size of thegraphene flake may result in a more pliable flexible portion 401 ascompared to the center portion 402. Conversely, the increased size ofthe graphene flake may result in a stiffer center portion 402 ascompared to the flexible portion 401. The size of the graphene flake mayvary between 1 micron in width to 500 microns in width.

The diaphragm 405 may also include graphene flakes or other graphenematerial that is oriented in one or more than one direction to providespecific mechanical properties. For example, the graphene flakes may beoriented such that a flake area of a significant portion of grapheneflakes are substantially aligned with an outer surface of the diaphragm405. Having the graphene flakes oriented in this way may result in adiaphragm 405 that has a decreased elastic modulus in a directionperpendicular to the flake area of the graphene flakes. If the diaphragm405 forms a conical- or dome-shaped shaped portion, as depicted in FIG.4, the stiffness of the dome-shaped portion may have an increasedstiffness or rigidity. Alternatively, the graphene flakes may beoriented along a different direction to provide a specific elasticmodulus resulting in a desired rigidity for the diaphragm 405. In someimplementations, the orientation of the graphene flakes is substantiallyrandomized and the composite material has an elastic modulus that issubstantially isotropic.

While varying concentration and/or size of graphene flakes may be usedto vary the stiffness of the diaphragm 405, graphene flakes may also beadded in improve the water resistance of the diaphragm 405. In someimplementations, graphene flakes 406 in various concentrations may beincorporated into the diaphragm 405 to reduce the water or moisturepermeability of the diaphragm 405.

In the embodiment depicted in FIG. 4, the diaphragm 405 is formed from aunitary structure having varying levels of graphene to define differentregions or portions, each region or portion having a differentstiffness. In an alternative embodiment, one or more of the regions maybe formed as a separate part that is attached to the one or more otherportions of the diaphragm. In some implementations, the separateportions may be bonded using an adhesive or other mechanical joiningtechnique. In some implementations, one or more separate portions may beover-molded or insert molded onto the other portion(s) of the diaphragm.

FIG. 5 depicts an example diaphragm 505 formed from multiple parts. Inparticular, the diaphragm 505 includes a membrane structure 512 and acomposite cap structure 515. The composite cap structure 515 may bebonded or otherwise mechanically joined to a surface of the membranestructure 512. The composite cap structure 515 may include a grapheneflake material 506 incorporated into a base material 510. Similar to theexamples described above, an increased concentration of graphene flakematerial 506 may result in a stiffer composite cap structure 515. Thecomposite cap structure 515 may define all or a portion of the centerportion 502 of the diaphragm.

As shown in FIG. 5, at least a portion of the membrane structure 512forms the flexible portion 501 of the diaphragm 505. The membranestructure 512 may be formed from a flexible material such as a polymer,rubber, or other similar material. In some implementations, the membranestructure 512 may include a lower concentration (including a zeroconcentration) of graphene flake material as compared to the centerportion 502, which includes the composite cap structure 515. Thecomposite cap structure 515 may form at least a portion of the centerportion 502 of the diaphragm 505.

FIG. 6 depicts a flow chart of an example process 600 for manufacturinga diaphragm for an audio device, such as a microphone or speaker.Process 600 may be used to manufacture a diaphragm similar to thediaphragms described above with respect to FIGS. 4 and 5.

In operation 601, a polymer material is prepared. The polymer materialmay be a liquid, which may facilitate the addition of a graphene orgraphene flake material. In some implementations, the polymer materialis in an uncured liquid state. A hardener or curing agent may be addedto polymer material in a subsequent operation to harden the polymermaterial to a solid state. In some implementations, the polymer materialis a thermoplastic polymer that is heated to a liquid or molten state.The polymer material may include a polyurethane, elastomer,fluoropolymer, synthetic rubber, or other similar material.

In operation 602, graphene flakes are added to the base material tocreate a composite mixture. The graphene flakes may be homogeneouslymixed into the polymer, they may be added to the surface of the polymeras a coating, or otherwise integrated with the polymer material. In someimplementations, graphene flakes are added to the polymer in quantitiessufficient to produce the desired flexibility or stiffness for variousportions of the diaphragm. In some embodiments, different size grapheneflakes are added to the polymer to produce the desired mechanicalproperties. The orientation of the graphene flakes may also becontrolled to produce a composite mixture having particular properties.

In general, a center portion of the diaphragm may include more grapheneflakes to make that area stiffer than the flexible portions to allowmore flexibility in the flexible portion where the diaphragm may beattached to a support. The diaphragm may include a center portionincluding the graphene flakes and a flexible portion formed about thecenter portion. A greater amount of graphene flake material may be addedto form to the center portion of a diaphragm as compared to a lesseramount of graphene flake material that may be added to form the flexibleportion of the diaphragm. In some cases, no graphene flakes are added toportions that correspond to the flexible portion.

With regard to operation 602, adding the graphene flakes may includevarying the concentration of the graphene flakes for two or moredistinct portions of the diaphragm. The size of the graphene flakes mayalso be varied as larger flakes will generally produce a stiffer endstructure while smaller flakes produce a more flexible structure. Insome implementations, multiple, separate composite mixtures are formed,each composite mixture having a different concentration and/or size ofgraphene flake, and each composite mixture may be used to form adifferent portion of the diaphragm.

Any portions of a diaphragm that are made separately may be joinedtogether. For example, separate portions may be joined using anovermolding process, insert molding process, or co-molding process. Theseparate portions may also be bonded or attached using an adhesive orother mechanical joining technique.

In operation 603, the diaphragm is formed by molding the compositemixture. The polymer and graphene composite mixture may be molded into aconical, conical dome, or other appropriate shape. Operation 603 mayinclude any one of a variety of molding processes including, forexample, injection molding, vacuum molding, pour molding, and the like.As part of the forming operation, the polymer graphene diaphragm may becured to produce a diaphragm having the desired characteristics.

In general, the forming operation 603 may produce a diaphragm havingvariations in graphene concentration. For example, a first concentrationof graphene flakes may be increased in a center portion of the domestructure as compared to a second concentration of graphene flakes in aflexible portion surrounding the center portion. The forming materialsmay include a first composite mixture having a first concentration ofgraphene flakes and a second composite mixture having a secondconcentration of graphene flakes that is less than the firstconcentration of graphene flakes. A center portion of the diaphragm maybe molded using the first composite mixture and a flexible portion ofthe diaphragm surrounding the center portion may be molded using thesecond composite mixture.

The forming operation 603 may also produce a diaphragm having variationsin graphene flake size. For example, the center portion may include afirst size of graphene flake and the flexible portion may include asecond size of graphene flake, where the first size is greater than thesecond size. The increased size of the graphene flake may result in astiffer center portion as compared to the flexible portion. Differentgraphene flakes may be used to firm a first and second compositemixture, each composite mixture having a different size and/orconcentration of graphene flakes. In some implementations, the centerportion may be formed from a first mixture having a first size grapheneflake that is larger than a second size graphene flake of a secondmixture used to form the flexible portion of the diaphragm.

The center portion may also be formed from two or more portions, Forexample, forming the center portion of the diaphragm may furthercomprise forming an inner center portion having a first concentration ofgraphene flakes and forming an outer center portion having a secondconcentration of graphene flakes that is lower than the firstconcentration. The flexible portion may also be formed having a thirdconcentration of graphene flakes that is lower than the secondconcentration.

In operation 604, the diaphragm may be installed in an acoustic device.For example, the diaphragm may be connected to a diaphragm support andvoice coil in accordance with the examples described above with respectto FIGS. 2 and 3. The acoustic device may form a speaker or microphoneand may be incorporated into a housing or other portion of a portableelectronic device. Operation 604 may be optionally performed as part ofprocess 600.

FIG. 7 is an illustrative block diagram of the electronic device 101shown in FIG. 1. Electronic device 101 can include display 703,processing device 704, a memory 705, an input/output (1/0) device 706, asensor 707, a power source 708, and a network communications interface709 connected on a system bus 710. Display 703 may correspond to thedisplay 103 depicted in FIG. 1. Additionally or alternatively, thedisplay 703 may include another display integrated into the device 101.The display 703 may provide an image or video output for the electronicdevice 101. Display 703 may be substantially any size and may bepositioned substantially anywhere on, and may be operatively associatedwith, portable electronic device 101.

The processing device 704 can control some or all of the operations ofportable electronic device 101. The processing device 704 cancommunicate, either directly or indirectly, with substantially all ofthe components of portable electronic device 101. For example, a systembus or signal line 710 or other communication mechanisms can providecommunication between the processing device 704, the memory 705, the 1/0device 706, the sensor 707, the power source 708, and/or the networkcommunications interface 709.

Processing device 704 can be implemented as any electronic devicecapable of executing instructions and carrying out operations associatedwith portable electronic device 101 as are described herein. Usinginstructions from device memory 705, processing device 704 may, using1/0 device 706, regulate the reception and manipulation of input andoutput data between components of the electronic device 101. Processingdevice 704 may be implemented in a computer chip or chips. Variousarchitectures can be used for processing device 704 such asmicroprocessors, application specific integrated circuits (ASICs) and soforth.

Processing device 704 together with an operating system may executecomputer code and manipulate data. The operating system may be awell-known system such as iOS, Windows, Unix or a special purposeoperating system or other systems as are known in the art. Processingdevice 704 may include memory capability in memory 705 to store theoperating system and data. Processing device 704 may also includeapplication software to implement various functions associated with theportable electronic device 101.

Memory 705 can store electronic data that can be used by the electronicdevice 101. For example, memory 705 can store electrical data or contentsuch as, for example, audio and video files, documents and applications,device settings and user preferences, timing signals, biometric imagessuch as fingerprint images, data structures or databases, and so on.Memory 705 can be configured as any type of memory. By way of exampleonly, memory 705 can be implemented as random access memory, read-onlymemory, flash memory, removable memory, or other types of storageelements, or combinations of such devices.

1/0 device 706 can transmit and/or receive data to and from a user oranother electronic device. One example of an 1/0 device is button 104 inFIG. 1 which may include a tactile switch. The 1/0 device(s) 706 caninclude a display, a touch sensing input surface such as a trackpad, oneor more buttons, one or more microphone devices 107 or speaker devices106, one or more ports such as a microphone port, and/or a keyboard.

The network communication interface 709 can facilitate transmission ofdata to or from other electronic devices. For example, a networkcommunication interface can transmit electronic signals via a wirelessand/or wired network connection. Examples of wireless and wired networkconnections include, but are not limited to, cellular, Wi-Fi, Bluetooth,IR, and Ethernet.

The foregoing description, for purposes of explanation, used specificnomenclature to provide a thorough understanding of the describedembodiments. However, it will be apparent to one skilled in the art thatthe specific details are not required in order to practice the describedembodiments. Thus, the foregoing descriptions of the specificembodiments described herein are presented for purposes of illustrationand description. They are not target to be exhaustive or to limit theembodiments to the precise forms disclosed. It will be apparent to oneof ordinary skill in the art that many modifications and variations arepossible in view of the above teachings.

What is claimed is:
 1. An electronic device comprising: a housingdefining one or more openings; a speaker diaphragm having a rigid centerportion surrounded by a flexible portion, wherein the speaker diaphragmis positioned within the housing, aligned over the one or more openingsand configured to generate sound waves that are emitted through the oneor more openings; a frame attached to the flexible portion of thespeaker diaphragm and secured to the housing; one or more magnetscoupled to the frame; and a magnetic actuator coupled to the speakerdiaphragm and configured to move relative to the one or more magnets. 2.The electronic device of claim 1 wherein the frame includes a gasketconfigured to form a seal between the frame and the housing.
 3. Theelectronic device of claim 1 wherein a magnetic force applied betweenthe magnetic actuator and the one or more magnets causes the speakerdiaphragm to generate sound waves.
 4. The electronic device of claim 1further comprising a mesh that is disposed between the speaker diaphragmand the one or more openings.
 5. The electronic device of claim 1wherein the speaker diaphragm is configured to generate sound waves bymoving along an axis oriented perpendicular to an interior surface ofthe housing.
 6. The electronic device of claim 1 wherein the rigidcenter portion includes graphene material.
 7. The electronic device ofclaim 1 wherein the speaker diaphragm, the frame, the one or moremagnets and the magnetic actuator are components of a speaker assembly.8. An electronic device comprising: a housing defining one or moreopenings; a speaker assembly positioned within the housing, aligned overthe one or more openings and including: a speaker diaphragm having arigid center portion surrounded by a flexible portion and configured togenerate sound waves that are emitted through the one or more openings;a frame attached to the flexible portion of the speaker diaphragm andsecured to the housing; one or more magnets coupled to the frame; and amagnetic actuator coupled to the speaker diaphragm and configured tomove relative to the one or more magnets.
 9. The electronic device ofclaim 8 wherein the frame includes a gasket that forms a seal betweenthe frame and the housing.
 10. The electronic device of claim 8 whereina magnetic force applied between the magnetic actuator and the one ormore magnets causes the speaker diaphragm to generate sound waves. 11.The electronic device of claim 8 further comprising a mesh that isdisposed between the speaker diaphragm and the one or more openings. 12.The electronic device of claim 8 wherein the speaker diaphragm isconfigured to generate sound waves by moving along an axis orientedperpendicular to an interior surface of the housing.
 13. The electronicdevice of claim 8 wherein the rigid center portion includes graphenematerial.
 14. A portable electronic device comprising: a housingincluding a back surface opposite a front surface and a plurality ofsidewalls extending between the front surface and the back surface; adisplay visible through the front surface; at least one buttonpositioned on an exterior surface of the housing; one or more acousticapertures defined by the housing; a frame positioned within the housingand secured to an interior surface of the housing; one or more magnetscoupled to the frame; a speaker diaphragm having a rigid center portionsurrounded by a flexible portion, wherein the speaker diaphragm ispositioned within the housing, aligned over the one or more acousticapertures and configured to generate sound waves that are emittedthrough the one or more acoustic apertures; and a magnetic actuatorcoupled to the speaker diaphragm and configured to move relative to theone or more magnets.
 15. The portable electronic device of claim 14wherein the frame includes a gasket configured to form a seal betweenthe frame and the housing.
 16. The portable electronic device of claim14 wherein a magnetic force applied between the magnetic actuator andthe one or more magnets causes the speaker diaphragm to generate soundwaves.
 17. The portable electronic device of claim 14 further comprisinga mesh that is disposed between the speaker diaphragm and the one ormore acoustic apertures.
 18. The portable electronic device of claim 14wherein the speaker diaphragm is configured to generate sound waves bymoving along an axis oriented perpendicular to an interior surface ofthe housing.
 19. The portable electronic device of claim 14 wherein therigid center portion includes graphene material.
 20. The portableelectronic device of claim 14 wherein the speaker diaphragm, the frame,the one or more magnets and the magnetic actuator are components of aspeaker assembly.